<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script !src="">
        alert("hello");//弹窗输出
        document.write("你好。")//页面输出
        console.log("你也好")//控制台输出
    </script>
</head>
<body>

</body>
</html>